1. Field of the Invention
The present invention relates generally to an information processing apparatus, an information processing method, a data recording medium, and an information processing system. More particularly, the invention relates to an information processing apparatus, an information processing method, a data recording medium, and an information processing system, in which digital data can be protected from illegal copying.
2. Description of the Related Art
Because of recent widespread use of networks, typically, the Internet, various types of information can be transmitted and received via networks. Accordingly, different types of information can be easily accessed, but on the other hand, the danger of making illegal copies of electronic publications is seriously increasing.
In particular, the following problems are encountered through the use of known networks. Even if the users illegally make copies of information received by their own terminals via networks and distribute the copies, it is difficult to determine the source of such copying.